Ventilating device having retractable hood



M y 1962 J. WATT ETAL 3,031,946

VENTILATING DEVICE HAVING RETRACTABLE HOOD Filed Sept. 18, 1959 s Sheets-Sheet; 1

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May 1, 1962 J. WATT ETAL VENTILATING DEVICE HAVING RETRACTABLE HOOD 3 Sheets-Sheet 3 Filed Sept. 18, 1959 f ,flaeaerA. Has-mp5 INVENTORS 9,4 4 75% 3,031,946 VEN I'ILATING DEVICEOHSVING RETRACTABLE James Watt, Pomona, and Robert A. Papsdorf, Claremont, Calif., assignors to Emerson-Pryne Company,

Pomona, Califl, a corporation of Delaware Filed Sept. 18, 1959, Ser. No. 840,825 11 Claims. (Cl. 98-115) The present invention relates generally to ventilating equipment including air exhausting devices and hoods mounted over cooking stoves to gather and remove fumes and warm air, and more particularly to a device of this character which combines in a single body structure an exhaust fan, a light, and air gathering means including an extension hood section which is retractable into the body structure when not in use.

Hoods for gathering and removing fumes and Warm air from cooking areas have been used for many centuries in the past. Hood structures have been biult into stoves and ranges and mounted on the walls and ceilings over cooking areas in kitchens, in communication with ventilating ducts; and are frequently equipped with fans or blow ers to maintain an outward movement of air. In the past, however, many of the hood devices have been individually designed and dimensioned to meet the requirements of each installation.

During recent years an increasing number of hood structures have been specified by architects and residential builders for use over fireplaces, stoves and barbecues, often being employed for their decorating as well as their ventilating value. More recently, a rather considerable amount of attention has been given to the convenient and functional arrangement of the kitchen areas of so-called contemporary homes. One conspicuous result of these efforts has been the division of the conventional kitchen stove into two or more sections, then placing the surface burner unit in the horizontal top of a counter and installing the oven, broiler and rotisserie units with their doors flush with vertical wall areas and opening at convenient work levels Well above the floor.

In many modern kitchen arrangements the burner units are installed in the counter-height tops of wall cabinets having cupboards below and either open or enclosed shelves above, the horizontal work space being clear from the counter edge back to the wall and vertically from the counter top to the first shelf extending outwardly from the wall. In other arrangements the cabinet is extended outwardly at right angles to the wall, and the shelves are suspended from the ceiling over the counter and burner unit.

This trend in kicthen planning made the need for means for removing cooking vapors from the burner areas immediately apparent, and a number of inverted pan-like rigid range hoods, attached to or supported from the undersurface of the shelf above the burner unit, have become generally available. However, those which have come within the scope of our observation and knowledge have appeared to be impractical in certain functional respects and difficult to adapt to many installations. Furthermore, they usually required that the exhaust fan be placed eiher in the ceiling or other comparatively inaccessible location, or that it occupy a. conspicuous posiion on the first shelf immediately above the hood.

In every case these rigid and stationary hood devices imposed a compromise on the part of the kitchen planner between providing a hood large enough to cover the burners properly and small enough to permit access to the burners and not hide them from view. Possibly the most important structural feature found to be lacking in the presently available stationary hoods is that of accessiice bility to the undersurfaces which is frequenly required to keep them grease free and clean.

Our present invention has been made with the foregoing considerations in mind, and is believed to have a number of important objectives.

One object of the present invention is the provision of a ventilating device having a fixed body attachable above or adjacent a cooking area, an outlet connectible to duct means adapted to direct exhaust air laterally or vertically of the body of the device, and an extendible portion that may be pulled out to increase the area over the stove from which vapors are removed.

Another object of our invention is the provision of a device of the character described having separately enclosed chambers containing the fan and illuminating means and a generally concave air-gathering hood member extendible outwardly therefrom to cover the entire burner area.

It is also an object of our invention to provide a fully self-contained hood, that is one which has a fan and/or light and all ancillary parts contained within the normal boundary surfaces of the hood.

A further object of our invention is the provision of a device of the character described and having rack and pinion means at opposite ends of the fixed body adapted to equalize the movement at the spaced ends of the extendible hood section.

A still further object of our invention is the provision of a device of the character described in which both the bottom panel of the fixed body and the extension hood section are provided with release means enabling their removal from the fixed body to facilitate cleaning.

An additional object of our invention is the provision of a range ventilating device provided with switches and operating means therefor effective to turn the light and fan on and off responsive to movements of the extension hood section.

:In brief, the ventilating device of our invention includes a generally rectangular body casing attachable to the undersurface of a shelf or structure above a cooking burner unit, the casing having depending side and end walls and a removable bottom panel disposed horizontally therein. A separate extension hood panel having upright and downwardly extended front and end portions, is adapted for interfitting engagement within the fixed casing and for sliding movement adjacent and relative to the removable bottom panel thereof. Release means are provided to enable the removal of both the extension hood and the casing bottom panel for cleaning purposes and to provide easy access to the interior of the casing in which an exhaust fan and a work light are disposed together with baflie means directing air from a grille in the panel to the fan and thence to the exhaust duct. Cam means carried by the extension hood and pressure sensitive switches in the casing cooperate sequentially to control the fan and light in response to movement of the extension hood.

Possible variations in the details and arrangement of the elements of the device, and additional objects of our invention will become apparent upon examination of the attached specification and the references contained therein to the accompanying drawings, of which:

FIG. 1 is a perspective of the ventilating device of our invention, shown with the extension hood section retracted inwardly of the casing and indicating the positionof the device when mounted on the undersurface of a cabinet.

FIG. 2 is an enlarged vertical cross section taken along the line and in the direction indicated by the arrows 2-2 in FIGS. 1 and 7, showing the device attached to the undersurface of a cabinet and indicating the position of the extension hood section when extended.

FIG. 3 is a further enlarged vertical cross section parallel to FIG. 2 but taken along the line 3-3 in FIGS. 1 and 7.

FIG. 3A is a fragmentary schematic diagram showing the switches also seen in FIG. 3, and indicating the manner in which they are sequentially engaged by cam means on the extension section of the hood.

FIG. 4 is an exploded perspective showing the major components of the ventilating device of our invention.

FIG. 5 is a vertical cross section taken along the line and in the direction indicated by the arrows 5-5 in FIG. 1', illustrating details of the slide mechanism and stop means for the extension hood section, and showing the manner in which the bottom panel of the device interflts and-is retained in the fixed casing.

FIG. 6 is an enlarged fragmentary vertical section taken along the line 66 in FIG. 5, showing details of the slide channel and rack of the extension section, and the supporting flanged pinion gear.

FIG. 7 is an inverted plan or bottom view of the device With the extension section removed and portions of the bottom panel broken away to show details of the fan, exhaust air ducting and lamp installation.

FIG. 8 is a fragmentary section and plan view of one corner of the device taken on the line 8 in FIG. 5.

FIG. 9 is a fragmentary perspective showing details of the splice box, with some parts broken away.

FIG. 10 is a fragmentary section in the plane of FIG. 2 showing an alternate mounting of the outlet duct flange to effect connection with a horizontal duct at the rear of the device;

Reference is now made to the perspective view of FIG. 1 in which a ventilating device constructed according to our invention and designated generally by the numeral 10, is shown in its normal position of use relative to a cabinet C and, in FIG. 2, to the cabinet C and the wall W to which the cabinet is attached.

However, for a better understanding of these and other views, attention is first directed to FIG. 4 in which the principal structural components of the assembly 10 are seen' to include three major members: a rectangular body or casing 11 having a top wall 12 with an air duct flange 13 and perforations such as 14 through which screws 15 pass for attaching the casing to the undersurface U of the cabinet in the manner indicated in FIGS. 2 and 3; a removable bottom panel 16 having therein airpassing grille 17, light aperture 18 which is normally covered by a pane of glass, oppositely extended hinge tabs 19 and 20 at the rear, tension springs 21 and 22 at the rear and a forwardly extended lip portion 23; and, lastly, a hood extension member 24 which is seen to be a drawer-like structure including a partial horizontal wall 25, a vertical front or face panel 26, and spaced vertical ends 27 and 28 of channel conformation with their open sides facing inwardly.

Partial wall 25, though in the lower portion of the extension member, may be viewed as a top wall of the member since it acts to deflect and direct vapors rising beneath it toward grille 17 through which they pass to be exhausted.

The removable panel 16 is secured within the casing 11 by engagement of the tabs 19 and 20 over angle brackets 33, seen best in FIG. 8 aflixed to and extended inwardly from the two end walls 29 and 30. With tabs 19 and 20 resting on brackets 33, if the panel 16 is then pressed rearwardly of body 11, thereby flattening the springs 21 and 22 against the inner surface of the back wall 34, the forwardly extending lip portion 23 can now be moved upwardly above and engaged with the inoent lower edge 35 of the front wall 36 of body 11. Tabs 19 and 20 define a horizontal pivot about which panel 16 swings to do this. Removal of the panel is effected by reversing the sequence of these movements. Panel 16 is pressed rearwardly to flatten springs 22 sufliciently that lip 23 disengages flange 35, allowing the front edge of the panel to swing downwardly about tabs 19 and 26. The interior of the housing is now fully available for servicing the fan or replacing the lamp globe, both mentioned later.

The channel-shaped ends 27 and 28 of the extension hood 24 fit adjacent and interiorly of the end walls 29 and 30 of the casing 11 and are supported by a pair of sprockets or pinion gears 31 and 32, in the manner illustrated with the gear 32 in the cross sectional view of FIG. 5 and the frontal view of FIG. 6.

As best seen in the sectional view of FIG. 6, the pinion gear 32 is preferably integral with and between concentrio circular flange 37 and cylindrical hub 33, which latter is rotatably received in a circular perforation 39 in the angular bracket 33. The unit consisting of the gear, its hub, and the attached circular flange, is provided with a square opening extending axially to receive the square shaft 46 which interfits in the same manner at the opposite end with the opposite unit including gear 31, as indicated in FIG. 3.

For reasons of economy in production it is preferable that gear 32 be cast or molded integrally with hub 38 and flange 37. This gear assembly can advantageously be made of a synthetic resin or plastic, for example, nylon, but of course the invention is not limited thereto. It will be evident from the drawing and the description herein that circular flange 37 functions as an anti-friction roller. Accordingly it may also be provided in the form of a separate disc located alongside'of or adjacent sprockct 32 and mounted to rotate with or rotate about shaft 4% The shaft thus serves to mount the gear and the weight supporting flange concentrically with each other.

The end walls 27 and 28 of the hood extension section 24 are oppositely facing as clearly shown in FIG. 6. The vertical wall 28 and the horizontal bottom panel 25 are both aflixed to an angular member 41, the upper edge of which is turned inwardly and downwardly and is serrated to provide a plurality of teeth 42 defining a continuous rack meshing with the teeth of pinion 32, as seen also in FIG. 5. Similarly, the pinion 31 is engaged by similar rack 43 adjacent the opposite wall 27 as seen in FIG. 3. The pinions 31 and 32 are caused to rotate in unison by reason of their mutual engagement with the square shaft 40. It will be noted, also, that the end of the shaft 49 has only a small clearance with a vertically disposed portion of the angle bracket 44 which is rigidly attached to bracket 33 of the casing 11, and thereby serves to limit endwise movement of shaft 46. Bracket 44 likewise prevents the gear 32 (or gear 31) from movement endwise of the square shaft.

A particular feature of the structure is the manner in which the weight of the hood extension 24 is carried by the pinion units 31 and 32. As will be understood from FIG. 6, the extended circular flange 37 adjoining gear 32 is larger in diameter than the gear and engages the undersurface of the inwardly turned section 45 of the angular channel member 41, whereby the interfitting teeth of'the rack 42 and the pinion 32' are permitted to engage but are not required to support the weight of the extension hood. Because the full weight is carried on the gear flange and not on the gear teeth, the teeth of the rack do not need to be accurately made to prevent bind ing. When the extension hood section 24 is retracted inwardly of the casing 11, the undersurface of the inbent section 45 may slide on the folded edge 46 of the vertical extension of the angle bracket 44. When the hood section 24 is drawn outwardly to the point of maximum extension, the inner end of the invent upper edge of the side 28 moves upwardly into sliding engagement with the undersurface of the angle bracket 33 immediately there'- above, as is also shown in FIG. 6. As the center of gravity of the hood extension moves to one side or the other of the support at flange 37, the hood extension rocks slightly about this support to raise or lower the inner end of the extension, this rocking being limited by the engagements described with bracket 33' or bracket 44;

Because of the synchronous movement in either til-rec tion of the interlocked pinion gears 31 and 32, the extension section 24 maybe extended by pulling on it at any point, such as 48 in FIG. 5, along the lower edge of the face panel 26, and retracted by inward pressure at any point on the face panel 26, without causing the section to twist laterally and bind in its guideways. The rack and pinion arrangement produces equal movement at both sides of the extension 24 and prevents one side from advancing faster than the other, thus causing the extension to bind in body 11.

Means for arresting the outward travel of the hood extension 24 at its normal limit are provided as indicated in FIGS. 5 and 6, and include a strap hook 49 attached as indicated at 50 to the bottom 25 of the extension section 24 and a stop 51 which extends downwardly from the channel section 33 which in turn is afiixed to the side 30 of the casing 11. The hook 49 is conformed, as best seen in FIG. 5, with a loop portion 52 disposed downwardly through an aperture 53 in the bottom surface 25, and is terminated upwardly in an angular tip portion 54 which as the extension section 24 is drawn outwardly by movement to the right in FIG. 5, is engaged as indicated at 54a by the downwardly disposed portion of the stop 51 at the normal position of maximum extension. However, as will be understood from the figure, the hook when in the engaged position indicated at 49a also serves as a latch and a downward pull on the loop portion 52a moves the hook end 54a beneath the stop 51 and permits the complete removal of the extension section 24 from the fixed casing 11;. Upon re-engage ment of the extension section 24 within the casing 11, the angular position of the end 54a upon engagement with the tab 51 depresses the loop section 52a downwardly through aperture 53a, thus enabling the end 54:: to pass the tab 51 without application of 'a manual pull on the loop 52a.

The interior arrangement of the ventilating device of our present invention will be clearly understood by reference jointly to FIGS. 2 and 7. As previously mentioned in connection with FIG. 1, the exhaust duct coupling flange 13 may be on top of casing 11 to connect with a duct (not shown) extending upwardly of the casing 11. As can be seen in FIG. 2, an aperture 55 is provided in the back wall 34 that is closed by a cover plate 56 when the upwardly directed outlet 13 is employed. To connect with a horizontally extending duct in the wall W, the cover plate 56 is transferred to the top wall 12 to close the opening 57 therein, and the duct coupling flange 13 is moved to the opening 55 in the rear side-wall 34, as shown in FIG. 10.

Depending from the inner surface of the top wall 12 of the casing 11 is an inner housing 58, best seen in FlGS. 2 and 7, which is attached to the top 12 by any suitable means such as angle brackets 59. Housing 58 is closed on its top side by wall 12 to form a separate and completely enclosed air passageway between the circular aperture 60 in the bottom wall of housing 58 and the opening 57 in the top wall 12 or the alternate opening 55 in the back wall 34. A fan 61 is attached by means of a mounting ring 62 having a plurality of bayonet type apertures 63 and by bolts 64 to the lower surface of the housing 58, as is also clearly shown in the sectional view of FlG. 2. The fan moves air through housing 53 from inlet 60 to outlet 57 or 55.

Also attached to the undersurface of the housing 56 is an angle bracket stiffening member 65 which serves to support an electrical connector or receptacle 66. The latter provides a convenient power source and readily accessible means for receiving the disconnectible plug 67 which is easily removed from receptacle 66 in case it is desired to remove the fan 61 for service or replacement. One end wall 68 of the housing 58 is disposed as seen in FIG. 7 at right angles to the rear wall 34 and serves structurally as a rigid point of attachment for the socket 69 in which the light bulb 70 is supported adjacent and above the light aperture 18 in the removable bottom 16.

In order to completely separate the air passageway interiorly of the housing 58 from the rest of the space within the fixed casing 11, a semicircular flange member 71 rises upwardly from the upper surface of the removable panel 16 as is best seen in FIG. 4. When the panel 16 isinstalled in the casing 11 as previously described and moved upwardly into engagement therein, the upper edge of the flange 71 becomes juxtaposed against the undersurface of the housing 58 and extends from each end of the angle bracket 65 completely around the fan mounting ring 62 substantially as indicated by the broken line 72 in FIG. 7. In this manner the flange 71 and the bracket 65 are jointly effective to close off the gap between the housing 58 and the upper face of panel 16, thereby increasing the effectiveness of the fan and substantially preventing entry of warm air and fumes into the interiorof the casing during normal operation of the fan.

Adjacent one end of the casing 11 a perforation is provided to receive a conduit fitting or an insulating grommet such as '73 and the connector cord 74 as shown in FIG. 7, and an alternate perforation 75 is provided in the top 12 as seen in FIGS. 1 and 4-. A splice box indicated generally at 76 in which the necessary electrical connections to the fan and light are made is provided adjacent the end 29 of the fixed casing. The splice box is formed by a partitioning panel 77 which is held in place by the wing nuts 78 and is readily removable to provide access to the power supply cord 74 to the voltage reduction transformer 79, the light and fan switches 80 and 81, respectively, and the fan speed selector switch 82 disposed interiorly of the splice box.

The splice box is shown in detail in FIGS. 7 and 9. It will be seen that two sides and two ends of the box are formed by top wall 12, end wall 29, front wall 36, and back wall 34 of the main body. Brackets 33 and 44 attached to the housing close one side of the splice box. The remaining side is closed by removable plate 76 which isolates the interior of the splice box thus defined from the space interiorly of the main body housing. All of this structure is located above panel 25 of the hood extension member 24.

The operation of the light 70 and the fan 61 in re sponse to movement and positioning of the extension hood section 24 is clearly shown in FIGS. 3 and 3A in which an elevated cam 83 is seen to extend upwardly from the Wall 25 of the extension section 24. The switches 80 and 81, which are of .the pressure sensitive type, are mounted with their respective plungers 8-4 and 85 extended downwardly through the undersurface of the splice box 76, and are aligned with the path of cam 83 so as to be engaged by its inclined leading edge 86. Thus, as is clearly illustrated in the fragmentary schematic diagram of FIG. 3A, when the extension hood section 24 is partially extended and cam 83 is thereby advanced to a position beneath switch 80, the actuating plunger 84 is forced inwardly of the switch 80 by the sloping leading edge 86 and is held inwardly by the top surface of the cam thereby closing the switch 80 and the circuit to the illuminating lamp 70 seen in FIG. 7. When the extension hood section 24 is completely extended the cam is moved farther to the position indicated by the broken lines at 87 in which the cam is beneath both switches 80 and 81, thereby forcing the plunger 85 inwardly of the switch 81 by engagement with edge 86 of the cam and completing the circuit through the speed selector switch 82 to energize the ventilating fan 61. The fan speed is changed from fast to slow by the use of the voltage reduction transformer 79 in the alternate circuit, and the speed selector switch 82 is actuated by manually operated push buttons 88 which are concealed by the face panel 26 when the extension hood section 24 is retracted as in FIG. 3, but are readily accessible when the hood section 24 is sufiiciently extended to energize the fan in the manner described above.

Switches 80 and 81 are preferably spaced apart in the direction of movement of cam 83 and the hood extension section 24 in order to be operated in sequence. For example, a short movement outward of the hood from its fully retracted position may first engage and close the lamp switch. A greater movement of the hood extension would cause cam 83 to engage and close the fan switch. With this arrangement, maximum visibility of the work surface and burners below the hood is afforded even when the light is turned on. When conditions require the use of the fan, the extension section is pulled out farther to increase the effectiveness of the fan. Of course the sequence in which the switches are engaged may be reversed if desired for any reason.

Because the switches 80 and 81 have normally open contacts, when the hood section 24 is completely removed from the fixed casing 11 the switch plungers 84 and 85 are free to move outwardly, thereby opening their contacts and breaking the supply of current to the light and fan.

From the foregoing description of our invention it can be seen that we have provided a self-contained ventilating device which is readily attachable above and adjacent cooking areas, completely encloses its own light, fan, switches, etc., and is adapted to gather warm air and direct it either vertically or laterally into conventional exhaust ducts.

It will also be seen from the above description that our invention provides a ventilating device having a generally compact fixed body which serves as a housing for the functional components and for the exhaust air ducts, and from which a movable portion of the air-gathering hood may be extended outwardly so as to completely cover the cooking burners therebelow.

It will also be apparent from the foregoing that our invention includes new and novel means for synchronizing the travel of the opposite ends of the movable hood section, and means for arresting its movement upon reaching the point of maximal extension.

Also from the above it can be seen that means have been provided for the removal of various structural elements whereby all of the interior functioning components are accessible for purposes of cleaning or inspection without removing the main body member from its position of fixed attachment to the supporting structure.

Further, it will be seen in the above description that our invention includes means by which the work light and ventilating fan are turned on and off responsive to the inward or outward movement of the hood extension.

It will be understood from the foregoing that various changes in the detailed construction or location of the elements of a ventilating device embodying ouriinvention may be made without departing from the spirit and scope of the invention. Accordingly, it is to be understoodithat the foregoing description is considered as illustrative of, rather than limitative upon, the appended claims.

We claim:

1. A self-contained ventilating device comprising:

a main body of generally rectangular shape, and including a top wall adapted for attachment to the bottom of an overhead support structure, and back, front and spaced end walls depending from the top wall, at least one of said back and top walls having an air outlet opening and said panel having an air inlet aperture therein;

a removable panel within said main body parallel to the top wall and spaced downwardly therefrom and above the lower edges of said depending walls to define a compartment within the main body and above the panel;

wall means within the main body and mounted on the top wall and cooperating therewith to define an air duct disposed within said compartment and having air inlet and outlet openings respectively cornmunicata ing with the air inlet aperture in the panel and the air outlet opening in one of the walls of the body to conduct air therebetween;

an exhaust fan in said duct forcing air to flow in the direction from the duct inlet opening to the duct outlet opening;

an extension hood including a top wall disposed below and generally parallel to the removable panel and extending between end portions or" the extension hood, said hood being below the duct and adapted to inter fit immediately beneath said removable panel and between the spaced ends of the main body;

and means at each end of the hood and connected to both the hood and the main body for slidably sup porting the hood on the end walls of the main body for movement of the hood substantially parallel to said removable panel between a retracted position in which the top wall of the hood covers at least a portion of the inlet aperture in the panel and an extended position in which the top wall of the head uncovers at least a portion of the inlet aperture in the panel to admit air freely to the duct and exhaust fan.

2. A self-contained ventilating device comprising:

a main body of generally rectangular shape, and including a top wall adapted for attachment to the bottom of an overhead support structure;

a removable panel within said main body parallel to the top wall and spaced downwardly therefromto define a compartment within the main body and above the panel; the main body also having a back wall and spaced end walls depending from the top wall to below said panel, at least one of said back and top Walls having an air outlet aperture and said panel having and air inlet aperture therein;

a duct disposed in said compartment and communicating between said apertures;

an exhaust fan in said duct;

an extension hood section including a top wall disposed below and generally parallel to said removable panel and extending between end portions of the extension section, said extension hood section being adapted to interfit immediately beneath said removable panel and between said spaced ends of said main body and being slidably retained therein and movably extendable outwardly relative to the front thereof to a position in which the top wall of the hood section uncovers at least a part of the inlet aperture to admit air freely to the duct and fan;

a pair of sprockets;

means rotatably mounting the sprockets on the main body one adjacent each of the end walls thereof;

a circular disc rotatably mounted concentric with each sprocket but of larger diameter;

means interconnecting the sprockets to cause them to rotate in unison;

and a channel-shaped member at each end of the extension hood section resting upon one of the circular discs with an adjoining portion of each channelshaped member overhanging the disc and having a depending flange with teeth meshing with the adjoining sprocket, whereby the movement of both sides of the extension section relative to the main body is equalized.

3. A ventilating device comprising:

a body section of generally rectangular outline and including a top wall adapted for attachment to the undersurface of a support structure, and spaced end walls depending from said top wall a support bracket attached to each of said depending walls;

a sprocket and means for rotatably mounting the sprocket at each bracket; means interconnecting the sprockets to cause them to rotate in unison; an exten sion hood section comprising a top wall, a front wall, and end walls at opposite ends ofthe hood section;

support means connected to the body section and to 9 the hood section including inter-engaging members Supporting the hood section for horizontal linear movement relativ to the body section;

and rack means mounted on the hood section at each end of the hood section and engaging a sprocket at the end of the hood section whereby rotation in unison of the sprockets equalizes the movement of both ends of the extension hood section relative to the support brackets.

4. A ventilating device as claimed in claim 3 in which the support means includes means providing a downwardly facing surface on the extension section and a rotatable supporting disc at and concentric with each sprocket engaging the downwardly facing surface on the extension section in weight supporting relation to support the extension-section independently of engagement between the adjacent sprocket and the meshing rack.

5. A ventilating device, comprising:

a main body of generally rectangular shape, and including a top wall adapted for attachment to the bottom of an overhead support structure;

the main body also having a back wall and spaced end walls depending from the top wall, one of the walls of the body having an air-passing aperture therein;

an exhaust fan mounted on the body to discharge air through said aperture; an extension hood section adapted to interfit between said spaced ends of said main body and being slidably retained therein and movably extendable outwardly relative to the front thereof;

switch means carried by the body to control supply of electricity to the fan;

and a switch operating cam carried by and movable with the hood extension section to operate the switch means and thereby energize the fan at a predetermined position in the range of movement of the extension section, said cam comprising means providing a pair of flat surfaces in spaced parallel planes interconnected by a transition surface.

6. A ventilating device as claimed in claim 5 that also includes:

an electric light socket mounted on the main body and adapted to receive a light globe;

a second switch means carried by the body in a position to be engaged by the switch operating cam and adaped to control supply of electricity to the socket, said switches being spaced apart in the direction of movement of the extension section and operated in sequence at predetermined points in the range of movement of the extension section. I

7. A self-contained ventilating device adapted for mounting beneath a cabinet or similar supporting structure, comprising:

a main body having a top wall adapted for attachment to the underside of said support structure and front, :back and end walls depending at the edges of said top wall;

means within the main body defining an air duct having a downwardly directed air inlet opening and an air exhaust opening, said exhaust opening of the duct being located adjacent and in communication with an air opening in one wall in the upper portion of the body;

an exhaust fan in the air duct;

an extension hood conforming to the shape of the main body and disposed in the lower portion of the body beneath the air duct and between the end walls of said main body;

and means slidably mounting the extension hood on the body comprising a support member adjacent each end of the main body and fixed relative thereto, each said support member having an aperture therein, a rotor member journalled in each said aperture at each end of the body; a pair of guides attached to a wall of the main body and extending parallel to said end walls, said extension hood having at each end a channel shaped member engaging one of said guides to direct movement of the hood and provided with a depending flange with downwardly disposed teeth, each of said rotors comprising a pinion gear portion engaging the teeth of an adjacent one of said depending flanges, and an interconnecting shaft rigidly attached at opposite ends to said rotor members.

8. A ventilating device as in claim 7 that also includes means providing a downwardly facing surface on the extension hood and a rotatable disc mounted on said shaft at each end thereof and engaging the downwardly facing surface in weight bearing relation to the extension hood.

9. A ventilating device as in claim 7 that also includes a fixed stop on the main body and a retractable latch member on the extension hood normally in position to engage said stop and limit travel of the hood outwardly of the main body, the latch being manually retractable to disengage the stop and permit removal of the extension hood from the main body.

10. The ventilating device as claimed in claim 7 that also includes an electric socket for an illuminating lamp mounted interiorly of said main body and characterized further by means for controlling said fan and said illuminating lamp, comprising:

a pair of switches;

means mounting the switches in said casing spaced apart in the direction of extension hood movement and with pressure sensitive actuators extended downwardly;

a cam having a relatively elevated camming surface mounted on said extension hood section in vertical alignment and engageable with said actuators and thereby efiective to close said switches sequentially to energize said light and said fan in response to.

outward movement of said extension hood section relative to the main body.

11. The invention as set forth in claim 10 wherein said switches are of the normally-open variety and are thereby effective to terminate the flow of current to said fan and said light when said extension hood section is removed from said casing.

References Cited in the file of this patent UNITED STATES PATENTS 818,003 Thorelius Apr. 17, 1906 2,349,668 Marker May 23, 1944 2,472,024 Olson May 31, 1949 2,535,707 Vezey Dec. 26, 1950 2,750,867 Meyer June 19, 1956 2,809,575 Floyd Oct. 15, 1957 2,836,114 Weaver May 27, 1958 

